There exists Level 1 evidence that surgical resection plus WBRT is a superior treatment modality than surgical resection alone in controlling local recurrence at the original site and in the brain overall (Kalkanis et al. 2010). Patchell et al. (1998) investigated the benefit of using WBRT as an adjunctive therapy following surgical tumor removal in these patients. The study randomized 95 patients to surgery alone or surgery plus WBRT. Progression of intracranial disease was fourfold greater in the surgery-alone group (70% compared with 18%, p < 0.001), and local recurrence was also higher in this group (46% compared with 10%, p < 0.001). Patchell et al. (1990) randomized 48 patients with single brain metastases to surgery and WBRT (25 patients) compared with WBRT alone (23 patients) and evaluated local recurrence and survival rates. In this study, the addition of surgery reduced the local recurrence in these patients from 52 to 20% (p < 0.02) and improved median survival from 15 to 40 weeks (p < 0.001). Patients in the surgery combined with WBRT arm also remained functionally independent for a longer period of time than those treated with WBRT alone (38 weeks compared with 8 weeks; p < 0.005).

Stereotactic radiosurgery is increasingly being considered as the first choice of treatment in many initial and recurrent cases of metastatic brain tumors because of its non-invasiveness, high control rate and lower rates of morbidity, in addition to it being an outpatient treatment modality. However, SRS fails to relieve the signs and symptoms of increased intracranial pressure and is unable to alleviate the mass effect of the tumor in an expedited fashion. Also, SRS is not considered optimal for lesions > 3 cm in diameter. SRS can increase peritumoral edema as well. The effectiveness of SRS compared to surgical resection has not been compared within a phase III randomized trial for patients with a single brain metastasis. Approximately six studies have been published comparing SRS and surgery. There exists level 2 evidence that surgical resection plus WBRT versus SRS + WBRT both present effective treatment options, resulting in relatively equal survival rates (Gaspar et al. 2010).

As in all surgical disciplines, patient selection is of paramount importance if desirable results are to be achieved. The patient should be medically fit to undergo surgery and to withstand the recovery phase postoperatively. Several studies have evaluated variables that might make some patients a better surgical candidate than others. Factors considered favorable for surgical resection of the tumor include age less than 65 years, KPS score > 70, single tumors, tumor size <3 cm, surgically accessible location, good control of extracranial disease and absence of leptomeningeal involvement, expected long disease – free survival and local symptomatic mass effect.

In 1997, Gaspar et al. (1997) performed a rigorous multivariable analysis of tumor characteristics, patient profiles and treatment variables extracted from three prospective Radiation Therapy Oncology Group (RTOG) brain metastases trials. This effort was made to analyze the relative contributions of pretreatment variables to the survival of patients with brain metastases using an interactive, nonparametric statistical technique known as Recursive Partitioning Analysis (RPA), to define the influence of treatment variations on survival among patients and to identify patient subgroups or stages. Three prognostic classes were developed for patients with multiple brain metastases (Table 18.2). Recursive partitioning analysis Class I patients are considered good candidates for craniotomy and resection, whereas Class III patients are not likely to realize benefit from surgery. This method of classification was later validated in 2000 (Gaspar et al. 2000). The RPA classification was also successfully applied to surgically resected and irradiated cases of metastatic brain tumors (Agboola et al. 1998). In another large single-institution retrospective study, preoperative performance status, symptomatic response to steroid treatment, systemic tumor control, and serum lactate dehydrogenase levels were found to be independent prognostic factors in patients with brain metastases (Largerwaard et al. 1999).

With recent advances in image-guided surgery and with increased utilization of newer modalities like functional MRI (fMRI), intraoperative MRI (iMRI), electrocorticography during awake craniotomy and diffusion tensor imaging (DTI), surgical resection is no longer considered “risky”, but has allowed neurosurgeons to safely navigate through the parenchyma and safely resect even deeply seated lesions with an acceptable risk of neurological deficit. DTI is a form of fMRI used to delineate white matter anatomy and is based on the principle that water preferentially diffuses along the long axis of white matter tracts. Distortions of white matter architecture secondary to a tumor or the edema surrounding a tumor can be mapped in a meaningful way to provide guidance during surgical resection. fMRI is a noninvasive imaging modality that uses cortical blood flow changes as a surrogate for increased or decreased neuronal activity. Functional MR imaging maps can be matched and fused with high-resolution MR or CT images to produce neuronavigational images, a process referred to as “functional neuronavigation.” The completeness of resection has also improved in recent years with increasing use of iMRI that provides instant feedback regarding residual tumor and helps overcome the problem of “brain shift”, an intraoperative phenomenon in which changes in tumor volume, cerebrospinal fluid drainage, intracranial pressure, or the use of brain retractors generate intraoperative brain deformation that renders preoperative neuronavigation registration inaccurate. Stummer et al. (1998) are credited with the development of a tumor-specific fluorescent marker that allows more accurate discrimination of infiltrating tumor from normal brain parenchyma, called 5-Aminolevulinic Acid (5-ALA). Although 5-ALA was used for resection of glial neoplasms initially, groups have applied the same concept successfully to metastatic brain tumors as well (Utsuki et al. 2007). With a paradigm shift towards minimally invasive neurosurgery that has always been an attractive option, both for clinicians and patients, several treatment modalities have surfaced recently. These modalities include such techniques as Laser Interstitial Thermal Therapy (LITT), cryoablation, and radiofrequency ablation. LITT has recently seen resurgence with regard to the clinical utility of this technique secondary to advances in MRI thermometry. Carpentier et al. (2008) recently reported the successful treatment of six patients with metastatic intracranial lesions using LITT.